MiniMax-H3-Longvideos

This node is a constant work in progress! If you are noticing bugs or features that do not work, please ensure that you are pulling the most recent version and updating your workflows.

H3-LongVideos

Long MiniMax-H3 video with synchronised audio from a single prompt, in ComfyUI.

H3 renders about 15 seconds at a time. This node turns a written scene into a chain of shots and joins them into one continuous video. Your text reaches the model word for word.

Install

Copy this folder into ComfyUI/custom_nodes/ and restart the ComfyUI server.

Requires ComfyUI 0.31+ with native MiniMax-H3 support (tested on 0.33).

What to load

UNETLoader ─┐                     images ─> Video Combine / Save Video
CLIPLoader ─┼─> H3-LongVideos  ─> audio  ─┘
VAELoader ──┘                     info   ─> Show Text

prompt is an input socket — wire a multiline text node into it.

Set plan_only first. It reports the shot split, the lengths and every warning, without rendering.

Writing the prompt

One paragraph = one shot, separated by a blank line. The first paragraph is the scene, prepended to every shot; the rest are beats.

Natural daylight, hard sun. A farm with a barn.

Dom drives a van down the driveway and stops in front of the barn.

Dom gets out and walks to the back of it.

Mara steps out of the barn and asks him: "Is that the last one?"

Dialogue goes in double quotes. Use the anchor widget if you want the framing carried separately — then every paragraph is a beat.

A line that must reach the model word for word

Put it on its own line inside the beat:

Mara walks Ana to the entrance.
exact: her wrists stay behind her back the whole way

It is placed straight after the beat, in your words, and nothing in the node reads, scopes, scrubs, reorders or drops it. That matters because the node's own continuity clauses compete for room: on a short beat they can be 70% of what the shot is told against the beat's 8%, and info reports that balance every run. An exact: line is not a guard and has no budget to lose.

Nothing reads it either, on purpose: a name in it puts nobody in the shot, a garment in it removes nothing, and a door in it stages no change. Write what must be said, and let the beat stage what happens. exactly: and verbatim: do the same thing.

To see your prompt entirely on its own, switch on the verbatim widget: a shot is then your scene, your beat and the sheet entries for the people it names, and nothing this node writes. Every failure the continuity clauses answer comes back with them — duplicate characters, invented speech, a drifting camera, a door that shuts itself, a walk played backwards — so it is most useful for proving whether a fault is the node's doing or the model's. info still lists what each clause would have said.

The character sheet

A paragraph of Name: attributes lines, or the character_memory widget. Each shot is given the entries for the people its beat names, and nobody else.

Nora: <Picture 1>, 34, she, tall, red hair, green canvas jacket, brown boots.
Mike: he, 41, dark hair, navy overalls.

• Declare a pronoun. It is what lets "he takes her coat off" find the right two people.
• Declare an age. Where a shot describes a bare region, the body named is the age the sheet states — without one, an unstated attribute is filled from the model's prior, which is a twenty-something whatever you wrote. A declared age under 18 gets no body described for it at all, and a sheet declaring a minor alongside a script that stages nudity or sex refuses to render.
• One name per person. Dan in some beats and Mike in others reads as two.
• Every name needs an entry, or the model invents that person differently each shot.

<Picture N> means ref_image_N, the socket. Tag it onto the person or thing it depicts and it follows them; untagged, a reference goes on every shot.

Settings

Ambience is mixed, never prompted. Scoring a silent shot from text needs the audio branch left open, and an open branch on a joint model invents a voice for the face to lip-sync to. The bed is built from the room your scene names, so it needs no file, and shaped noise cannot speak. It makes tone — air, rumble, hum, water, a clock — so a scene whose ambience is birdsong gets the room, not the birds; info says when.

Everything else is a switch, on by default, and each has a tooltip explaining what it does and what it costs. Hover before you change one.

Outputs

When a shot renders something you did not expect, read script. It shows precisely what that shot was told, and info says why.

Other nodes here

• H3 Shot Length — seconds to a valid H3 frame count.
• H3 Overlay — watermark and intro title composited onto finished frames.
• H3 Model Inspector — checkpoint precision, and whether your card runs it natively.

Notes

• No negative prompt: H3 is CFG-free at cfg 1.
• No denoise control: fixed at 1.0, because partial denoise desyncs the joint audio/video schedule.
• Widgets are restored by position. If they read NaN, right-click the node → Fix node (recreate), set your values, and save the workflow again.

Disclaimer

The owner of this repo will not be responsible for any copyright strikes incurred because of use. You are responsible for your works. Use this node responsibly and ethically.